Not international books; I have different shipping addresses set for UK and US and one common billing address (UK) and haven't had any issues with buying books which were unavailable on the UK store from Amazon US (just need to select the US address as the shipping one). I even bought one game from there (Awesomenauts DD) and it went through without any problems.
Maybe I haven't bought that many, just around 50-60 books from the US store.
I don't think availability on the UK/US store has anything to do with it. If the book isn't meant for "international" use (FYI, they don't appear to mention this on store pages), it will ping them to send the email asking for that information. Games don't cause the same thing. It is only e-books that this happens with.
I purchased one book in a £1 sale, using my UK billing address. Within hours, they emailed me asking for my passport (seeing as I don't have Military ID or a Valid UK driver's license).
The email, for the record, reads as follows:
I see that you attempted to purchase "BOOK TITLE" while in a different country than United Kingdom listed on your Amazon account. Certain Kindle titles are not available everywhere. We are reaching out to you to ensure the best possible service for your account.
If you have moved to a different country, you can easily update your country for your Amazon account at
If this is not the case, and you would like to share information that you live in United Kingdom, we can be reached by fax at NUMBER from outside the UK, or NUMBER from within the UK. Helpful information includes:
– Military ID
– Driving Licence
We want to assure you that we handle this information in a secure manner: these are dedicated fax lines, staffed in an area with limited employee access. The fax is never printed, just converted to an electronic image that is used to check the country, then the image is deleted.
To clarify. Some books sold on Amazon are specified (internally) as being for "international" use. That means it doesn't matter where you are, you can buy it from any Amazon site, even if your local Amazon site doesn't sell it. However, some books are specified (internally) as being for that region only. Attempting to purchase one of those, will allow the purchase to go through, but also results in the above email being sent out several hours later.